Neuro VI Flashcards
Common causes of noncommunicating hydrocephalus?
1) stenosis of aqueduct of Sylvius
2) colloid cyst blocking foramen of monro
3) tumors
Differentiating ex vacuo ventriculomegaly from hydrocephalus
ICP normal in ex vacuo ventriculomegaly
Common causes of ex vacuo ventriculomegaly
1) AD
2) advanced HIV
3) Pick disease
Total # of spinal nerves and breakdown
31 8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal
Rules about where nerves exit
1) C1-C7 exit above corresponding vertebra.
2) C8 exits below C7 and above T1.
3) All other nerves exit below (eg C3 exits above 3rd cervical vertebra; L2 exits below 2nd lumbar vertebra)
most common locations of herniated disc
L4-L5
L5-S1
Where does spinal cord end in adults?
Lower border of L1-L2
Where does subarachnoid space extend to in adults?
Lower border of S2 vertebra.
LP location?
L3-L5, keep the cord alive.
Gracilis vs. cuneatus
Organized as you are with Arms and hands outside, legs inside.
If you see a sympathetic horn what does that tell you?
Between T1 and L2/L3
Tract locations in spinal column…
FA 472
Organization of lateral spinothalamic tract…
Sacral out wide, cervical medial.
*Legs lateral.
anterior vs. lateral spinothalamic tract
Lateral = pain, temperature anterior = crude touch, pressure.
lateral corticospinal tract organization
sacral lateral, cervical medial.
*legs are lateral
ascending vs. descending pathways
dorsal column + spinothalamic tracts carry ascending information.
CS tract carries descending information.
location of crosses in tracts
Ascending tracts (dorsal column, spinothalamic) synapse and then cross.
Dorsal column pathway
1st order neurons are sensory neurons with cell body in DRG –> enters spinal cord, ascends ipsilaterally in dorsal column –> synapses with ipsilateral nucleus cuneatus or gracilis in the medulla –> 2nd order neuron decussates in medulla –> ascends contralaterally in medial lemniscus –> synapse 2 on VPL in thalamus) –> 3rd order neuron projects to sensory cortex.
Spinothalamic tract pathway
sensory nerve ending (alpha delta or C fibers) has cell body in dorsal root ganglion, enters spinal cord –> synapse 1 in ipsilateral gray matter in spinal cord –> decussates at anterior white commissure –> ascends contra laterally –> synapses on VPL in the thalamus –> 3rd order neuron projects to sensory cortex.
Lateral CS tract pathway
UMN neurons have cell bodies in motor cortex –> descend ipsilaterally through IC –> most fibers decussate at caudal medulla (pyramidal decussation) –> descends contra laterally –> synapses on cell body of anterior horn in spinal cord –> LMN leaves spinal cord and synapses at NMJ.
**2 neuron pathway.
Weakness: UMN or LMN sign?
both
Muscle tone in UMN and LMN
Increased with UMN, decreased with LMN
spastic and flaccid paralysis for UMN and LMN
spastic paralysis = UMN lesion
flaccid paralysis = LMN lesion
syndromes affecting anterior horn?
1) polio
2) werdnig-Hoffmann
werdnig-Hoffmann prognosis
Median age of death of 7 months
Difference in presentation with polio vs. werdnig-Hoffmann
Polio –> asymmetric weakness
werdnig-Hoffmann –> symmetric weakness
Where will ALS affect spinal cord?
Combined UMN and LMN, so anterior horn + lateral CS tract
ALS presentation
1) asymmetric limb weakness (hands/feet)
2) fasciculations
3) eventual atrophy
4) *preserved sensory and bowel/bladder functions
ASA occlusion presentation on spinal cord cutout?
Everything affected except dorsal columns and Lissauer tract
What is the watershed area with ASA and why?
Upper thoracic territory because artery of Adamkiewicz supplies ASA below T8
Tabes dorsalis affects…
posterior column.
Tabes dorsalis pathophys
demyelination of dorsal columns and roots leading to progressive ataxia.
tabes dorsalis exam
1) positive romberg sign
2) absence of DTRs
tabes dorsalis associations
1) charcot joints
2) shooting pain
3) Argyll Robertson pupils
subacute combined degeneration presentation
1) ataxia
2) paresthesia
3) impaired position/vibration sense
How does polio virus get around?
Replicates in oropharynx and small intestine then spreads via bloodstream to CNS.
How do you recover polio virus?
from stool or throat.
CSF findings in poliomyelitis?
1) increased WBCs
2) slight increase of protein
What is frataxin?
iron binding protein
cell bio problem with Friedrich’s?
impaired mitochondrial functioninig
Childhood presentation of Friedrich’s?
Kyphoscoliosis
What is brown-sequard?
Hemisection of spinal cord
brown-sequard presentation
1) ipsilateral UMN signs below level of lesion
2) ipsilateral loss of tactile, vibration, proprioception sense below level of lesion
3) contralateral pain and temp loss below level of lesion (due to spinothalamic tract damage)
4) Ipsilateral loss of all sensation at level of lesion
5) Ipsilateral LMN signs at level of lesion
6) Horner syndrome if above T1
Horner syndrome and brown-sequard pathophys
Due to damage of oculosympathetic pahway
Whee is gallbladder pain referred to?
right shoulder via phrenic nerve.
Referred right shoulder pain think…
Diaphragm or gallbladder
C2 dermatome
posterior half a skull cap
C3 dermatome
high turtleneck shirt
C4 dermatome
low-collar shirt
C6 distribution
thumbs
T4
nipple
T7
xiphoid process
T10
umbilicus
L1 location
inguinal ligament
kneecap dermatome
L4
Dermatomes related to erection and sensation of penile and anal zones?
S2,3,4.
S2,3,4 keep the penis off the floor
triceps reflex
C7,8 “C7,8 lay them straight
cremaster reflex nerves
L1,L2– “testicles move”
anal wink reflex nerves
S3,S4 “winks galore”
